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    <title>Document</title>
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<body>
    <script>
        //1. 创建xhr对象
        var xhr = new XMLHttpRequest();
        // 2.调用open函数
        xhr.open('POST', 'http://www.liulongbin.top:3006/api/addbook');
        // 3.设置Conten-Type属性
        // 给post请求头设置一个Conten-Type属性
        xhr.setRequestHeader('Content-type', 'application/x-www-form-urlencoded')
        // 4.调用send函数
        xhr.send('bookname=三国演义&author=王三&publisher=上海出版社')
        // 5.监听onreadystatechange事件
        xhr.onreadystatechange = function () {
            if (xhr.readyState == 4 & xhr.status == 200) {
                console.log(xhr.responseText);
            }
        }
    </script>
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